The present invention relates generally to test fixtures. More particularly, the present invention is concerned with a test fixture for measuring the squareness of springs, cylindrical objects or the like.
The "squareness" of a spring is becoming an increasingly important factor. As will be appreciated by those skilled in the art, manufactured springs deviate from perfect squareness for a variety of reasons. Deviation occurs because, for example, of the characteristic resiliency of the wire or cable wound to produce the spring. A variety of other factors may also effect the characteristics of the spring product. In a perfectly "square" spring its flat ends will be parallel with one another, and both will be perpendicular with respect to the axis of the spring. In other words, a perfectly square spring will be generally of the form of a cylinder. However, in actual practice, the ends of the manufactured spring are not perpendicular to the spring axis; thus a deviation in squareness occurs.
Those skilled in the art have long been familiar with such deviation. For most manufacturing purposes deviations in squareness of approximately Two to Four degrees have been acceptable. However, increasingly precise squareness tolerances have been demanded in modern products requiring precision springs. For example, it is not uncommon to find that required spring squareness deviation must be within limits less than One degree.
Hence it is desireable to provide some form of test fixture with which the "squareness" of a spring may be quickly and easily checked by the manufacturer. The closest "prior art" known to me involves dissimilar apparatus only vaguely related to my invention, shown in U.S. Pat. Nos. 1,148,196 and 1,699,619.